Ecology and Evolution of Adaptations
systems and life history evolution...
Evolution of alternative life histories in bluegill
bluegill have two discrete life histories that mature at different
ages. Female bluegill have a single life history. The blue portions
of the arrows represent sexual maturity.
boat house on Lake Opinicon.
experimental pool facility at QUBS.
Mate choice and genetic benefits in guppies
male (top) and female guppy. Photo provided courtesy Dr Anne Houde.
Aripo river in Trinidad.
males are characterized by a discrete polymorphism in life histories
termed "parental" and "cuckolder". In Lake Opinicon,
where field research is conducted, parental males mature at about
7 years of age and compete to construct nests in densely packed
colonies. Nesting males court and spawn with females and provide
sole parental care for the developing eggs and fry in their nests.
By contrast, cuckolder males do not build nests of their own or
care for their offspring. Cuckolders mature precociously and steal
fertilizations in the nests of parental males through two tactics:
"sneakers" (age 2-3 years) hide behind plants and debris
near the nest edge, but are visible after darting into the nest
during female egg releases; "satellites" (age 4-5 years)
are about the size of mature females (age 4-8 years) and by expressing
female colour and behaviour are able to mislead parental males into
identifying them as second females in the nest. Cuckolders die before
the age of mature parentals and never become parentals themselves.
research on bluegill is conducted every summer at Queen's University
Biological Station (QUBS). QUBS is located on the shores of Lake
Opinicon, one of the lakes of the Rideau Canal, about 50 km north
of Kingston, Ontario. The main facility consists of 32 buildings,
including the Operations Centre, a library, conference rooms, lab
spaces, a workshop, an aquarium house, and an experimental pool
facility. Accommodations range from one-person sleeping cabins to
large cottages and dormitory space. Although several of the Station's
buildings are original, dating back to the late 1940's, others have
been added to provide comfortable accommodations for up to 80 researchers.
The station now boasts a fleet of boats, reference collections,
and audiovisual, optical and electronic equipment, including an
automated weather station. To visit the QUBS website, click
Guppies are a small tropical fish native to Trinidad and Venezuela.
They have internal fertilization and give birth to live young. Females
are highly selective among potential mates even though males provide
only sperm and hence genes to the female. Work in my lab has been
addressing the potential benefits to female choice in such non-resource
based mating systems. My lab has proposed that mate choice by females
can increase the genetic quality of their offspring through either
GOOD GENES or COMPATIBLE
GENES. Good genes have a positive fitness
effect independent of the other genes in the genome and consequently
have additive genetic variance. In contrast, compatible genes have
positive fitness effects only when in a specific combination with
other alleles (overdominance) or genes (epistasis) and consequently
have non-additive genetic variance. Sexual signals such the orange
colouration on the integument of males (see photo) or the courtship
display of males may indicate their good gene genetic quality. Odour
cues may indicate compatible gene quality at, for example, the genes
of the MAJOR HISTOCOMPATIBILITY
COMPLEX, which are involved in the immune
response and are found in all vertebrates.